While the present invention is subject to a wide range of applications, it particularly relates to a hybrid cord, such as can be used to reinforce elastomers. More particularly, the present invention is directed to a hybrid cord construction used to reinforce rubber articles, such as belts, hoses and tires.
In a conventional rubber article, such as a tire, the fatigue properties of the metal cord reinforcement are degraded, mainly by material fatigue due to repeated strain and fretting wear in the contact portion between the adjacent filaments. The high cord tension strongly increases the contact pressure between steel filaments. The cord bending will generate a relative movement between the filaments heavily pressed against each other, leading them to severe fretting. The best way to decrease the fretting failure from the cord construction standpoint is to reduce the contact pressure between the filaments under high tension forces. Conventionally, a rubber layer is interposed between the parallel filaments. Unfortunately, not all cords are sufficiently xe2x80x9copenxe2x80x9d enough to permit an adequate amount of rubber to penetrate the spaces between the filaments in the cord. Therefore, there exists a need for a cord which by its very construction the fretting wear will be reduced.
The present invention relates to a hybrid cord for the use in the reinforcement of elastomers. The hybrid cord has
(A) a core steel filament;
(B) a first layer of one or more nonmetallic filaments which are wrapped about the steel filament in the core; and
(C) a second layer of from 4 to 12 steel filaments which are wrapped about the first layer.